1. Field of the Invention
The present invention relates to an image control apparatus for obtaining a copy having an image of proper density.
2. Description of the Prior Art
In an apparatus of the type described above, a photodetecting means or a latent image potential detecting means of a photosensitive drum first measures a density of reflected light from an image on an original or a portion thereof. Then, a light source for illuminating an original or a development bias is controlled according to a detection signal, and a light intensity of the light source or the development bias voltage is set, thereby obtaining an image having a proper density.
However, according to this method, if the original has an image whose respective portions have different densities, a portion having a low density is copied to be too dark, and a portion having a high density is copied to be too light. Also, a density of reflected light from an image on the original is measured by the photodetecting means or the latent image potential detecting means of the photosensitive drum upon performing the copy operation, and simultaneously, the light intensity of the light source or the development bias is controlled according to the measured density, thereby obtaining an image having a predetermined density. However, in this method, when the original has an image whose respective portions have different densities, considerable density variations occur undesirably.
Such a conventional apparatus has a special detecting means for detecting a density or a contrast of an image on an original. In accordance with information of the density or the contrast of the original obtained from the detecting means, an application voltage of the light source for illuminating an original or the development bias voltage is controlled so as to obtain a copy having a proper density. However, even if the application voltage or the development bias voltage is controlled in such a manner, not all originals result in images with good contrast. In a conventional copying machine, the copy operation is unsatisfactorily performed to produce an original having such a poor contrast image.